Three dimensional cam mechanism



July 15, 1958 L. A. PRENTICE THREE DIMENSIONAL CAM MECHANISM Filed March 5, 1956 LEON A. PRENTICE INVENTOR.

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mm F ATTY United States atent THREE DIMENSIONAL CAM MECHANISM Leon A. Prentice, Portland, Greg. 7

Application March 5, 1956, Serial No. 569,542

2 Claims. (Cl. 123-90) This invention relates to improvements in internal combustion engines and more particularly to the valve operating and actuating mechanism for such engines.

It is one of the principal objects of the invention to improve, simplify, make more accurate and less affected by wear, and render fully interchangeable the valve operating mechanism of internal combustion engines, to avoid the necessity for any separate cam shaft and eliminate all gearing and gear noise in such mechanism.

To this end, the invention provides means for actuating a plurality of valves through the operation of a single cam cylinder, novel means being provided for alternately acting upon the intake and exhaust valves of one or more engine cylinders.

The foregoing and other objects will appear as my invention is more fully hereinafter described in the following specification, illustrated in the accompanying drawing, and finally pointed out in the appended claims.

in the accompanying drawing:

Figure 1 is a fragmentary sectional view illustrating the invention applied to a single cylinder engine.

Figure 2 is a side view on an enlarged scale of the cam cylinder shown in Figure 1.

Figure 3 is a top plan view of Figure 2 with the superimposed parts shown in broken lines.

Figure 4 is a fragmentary sectional view illustrating the invention applied to a multiple cylinder engine.

Figure 5 is a fragmentary sectional detail view on an enlarged scale of the cam cylinder, groove follower, cam shoe and valve lifter.

Figure 6 is a view illustrating diagrammatically the relation of the cam elements to each other throughout the circumference of the cam cylinder.

Referring now more particularly to the drawing:

In Figure 1 reference numeral 1 generally indicates the block of a conventional single cylinder internal cornbustion engine having intake and exhaust ports 2 and 3 respectively controllable by intake and exhaust valves 4 and 5. The valves by their stems 6 and 7 are slidably mounted in guides 8 and 9 below which the stems extend and are surrounded by compression springs 11' and 11 hearing against manual lash adjustments indicated gen erally at 12 and 13 between the bottom ends of the stems and valve lifters 14 and 15. Each lifter is concentric with its respective valve stem and rotatably and slidably mounted in vertical bearings 16 and 17 formed in the engine block 1.

As best shown in Figure 5, each cam lifter is provided with an eccentrically disposed opening 18 to serve as a hearing by means of which it is operatively attached to a pin 19--2G (Figure 1) formed integral with or secured to a combination groove follower or tracer and olfsct cam shoe indicated respectively at 2122 for the intake valve 4 and at 2324 for the exhaust valve 5.

A cam cylinder indicated generally at 25 is secured in a conventional manner to the engine crankshaft 26 which rotates in a clockwise direction as viewed in Figure 1. The peripheral surface of the cam cylinder is provided with a pair of parallel groves 27 and 28 which intersect or cross as at 29. Cams 30 and 31 are provided respectively adjacent the grooves 27-28 and converge toward the intersection 29 as shown. The circumferential spacing between the converging ends of the cams is equal to the amount .of overlap at their opposite ends representing the mechanical separation of the intake and exhaust valves.

With the cam cylinder rotating clockwise as shown in Figure 1 it will be noted that the intake valve 4 has just been lifted into an open position where it will be held by the cam 31 through degrees rotation thereof throughout the intake stroke of the engine and that the exhaust valve 5 has dropped from the cam 30 into a closed position. At the beginning or return of the compression stroke the cam 31 will have rotated another 180 degrees thereby permitting the intake valve to be reseated. Both valves will remain seated during the following 180 degrees of rotation of the power stroke for the reason that their respective tracers and cam shoes, having gone through the crossover 29, have thereby transposed the shoes from the operative or cam sides of the cam cylinder to the inoperative peripheral surface 32 thereof between the grooves 2728. At the completion of the power stroke the leading end of the cam 30 will engage the cam shoe 24 of the exhaust valve 5 for the reason that its tracer 23 having again passed through the crossover 29 will have relocated the shoe in the path of movement of the cam 30. The cam shoe 22 of the intake valve also having gone through the crossover will now be in the path of the oncoming end of the cam 30 at the termination of the exhaust stroke. Lateral movement of the tracers as they pass through the crossover from one groove to the other is permitted by the rotatable mounting of their respective lifters 14 and 15 as aforesaid. Thus it will be seen that the intake and exhaust valves will each open and close once in proper sequence during two revolutions of the crank-shaft of a 4-cycle internal combustion engine.

In Figure 4 I have shown the invention applied to a two cylinder engine but it will be readily understood that the invention can be successfully applied to any number of in-line' cylinders in a single bank or in opposed banks or to a radial engine whose number of cylinders can be determined by the diameter of cam cylinder 25A necessary to accommodate my valve actuating mechanism for each cylinder.

With particular reference to Figure 4, the valve actuating mechanisms, identical with that shown in Figure 1, are designated as being associated with No. 1 cylinder and No. 2 cylinder of a two-cylinder four-cycle engine whose pistons are connected to the crank-shaft 26A in the conventional manner. The cam cylinder 25A secured to the crank-shaft 26A is identical with that shown in Figures 1 to 3 and also rotates clockwise. The intake valve 4A and exhaust valve 5A of No. 1 cylinder are positioned for the beginning of the intake stroke and their subsequent functioning is the same as that described in reference to Figure 1. The intake and exhaust valves 35 and 36 respectively for cylinder N0. 2 are actuated by their respective tracers 3738 and cam shoes 39-44) working within the grooves and upon the cams of the cam cylinder. In the positions shown the exhaust valve 36 has just opened and will be so held until the expiration of the exhaust stroke when the cam 31A has rotated 180 degrees at which time the intake valve 35, whose tracer has now passed through the cross over, will be opened by the cam 30A. Thus the firing order of the power impulses will be No. 1 cylinder at 0 degrees, No. 2 at 180 degrees, No. 1 again at 540 degrees, and No. 2 at 720 degrees.

The cam cylinder when installed in any engine will be on the interior of the crankcase to thereby insure adequate lubrication for all of its related parts.

While I have shown particular forms of embodiment of my invention I am aware that many minor changes therein will readily suggest themselves to others skilled in the art without departing from the spirit and scope of the invention. Having thus described my invention what I claim as new and desire to protect by Letters Patent is: V

I claim:

1. In an internal combustion engine, the combination of :a plurality of spaced apart reciprocal intake and exhaust valves operable by slidably and rotatably mounted valve lifters, a crankshaft, a single cam cylinder on said crankshaft for operating all of said valves and having a pair of peripheral grooves of uniform diameter concentric with said cylinder and said crankshaft and intersected at a point in their circumference, a cam adjacent one side of each groove extending through 180 thereof in opposite directions and converging toward said intersection at one of their ends and overlapping at their other to an extent equal to the mechanical separation of said valves, a tracer disposed in each groove and pivotally connected to said slidable and rotatable valve lifters, each tracer being provided with a cam shoe laterally offset from said grooves and movable by its tracer into and out of the path of movement of said cams whereby said valves will be intermittently opened by engagement of the cams with said cam shoes.

2. In an internal combustion engine, the combination of a plurality of spaced apart reciprocal intake and exhaust valves operable by slidably and rotatably mounted valve lifters, each of said valve lifters comprising a vertically reciprocal and rotatably mounted disc having a top surface and a bottom surface concentric with its respective valve stem and provided on its top side with a lash adjustment and on its bottom side with an eccentrically disposed downwardly opening aperture, a crankshaft, a single cam cylinder on said crankshaft for operating all of said valves and having a pair of peripheral grooves of uniform diameter concentric with said cylinder and said crankshaft and intersected at a point in their circumference, a cam adjacent one side of each groove extending through 180 thereof in opposite directions and converging toward said intersection at one of their ends and overlapping at their other to an extent equal to the mechanical separation of said valves, a tracer disposed at all times in each groove and integrated with a cam shoe laterally offset from the grooves, each tracer being provided with an upwardly extending pin journalled in the said downwardly opening aperture of its respective cam lifter, and each shoe being thereby movable by its tracer into and out of the path of movement of said cams whereby said valves will be intermittently opened by engagement of the cams with said cam shoes.

References Cited in the file of this patent UNITED STATES PATENTS 1,177,428 Melin Mar. 28, 1916 1,541,069 Peters June 9, 1925 1,614,830 Crandall Jan. 18, 1927 FOREIGN PATENTS 951,084 France Apr. 11, 1949 

